Generally, a gyroscope is a measuring instrument that detects an angle and an angular velocity of an object, and is also called a gyro or a gyro sensor. The gyroscope is used for autonomous navigation of a ship, an aircraft, or a rocket. Recently, the gyroscope is used also in a car navigation system, a self-driving system, a robot, a digital camera, a spydrone, or the like.
In addition, in recent years, there are more and more chances to photograph a still image using a small-sized camera for a mobile phone. Accordingly, various optical image stabilizers (OIS, hereinafter, referred to as image stabilizers) that can make a sharp image by preventing image blurring on an imaging plane even if there is camera shake (vibration) when photographing a still image has been conventionally proposed.
As this type of image stabilizing system, an optical system, such as a sensor shift system or a lens shift system, and a software system in which image stabilization is performed by image processing with software are known.
The sensor shift system has a configuration in which an imaging element (CCD or CMOS sensor) can move centering around a reference position by an actuator. In addition, the lens shift system has a structure in which a correction lens moves for adjustment in a plane perpendicular to an optical axis. Furthermore, in the software system, for example, a noise component is removed from a detection result of a detection means, and specific information necessary for correction of image blurring due to camera shake of an imaging device is calculated from a detection signal from which the noise component is removed, so that, in the state where the imaging device is still without camera shake, a captured image is also still. In addition, an image stabilizer in which camera shake is corrected by shaking a lens module (or camera module) itself that holds a lens and an imaging element has also been proposed.
For example, PTL 1 describes an image stabilizer capable of correcting camera shake generated when a still image is photographed by a small-sized camera for a mobile phone to photograph an image without image blurring. The image stabilizer is provided in an auto focus (AF) camera drive device, and a permanent magnet is used in common to reduce the number of components. As a result, the size (mainly, height) of the image stabilizer is made small (low).
In addition, in a camera device mounted on a mobile phone, in order to reduce the size and the cost, the drive system of a camera lens is not closed-loop control but is usually control in which a lens position is not fed back to a lens position control unit (hereinafter, referred to as open-loop control). According to this, for example, PTL 2 proposes an actuator drive device that drives an electromagnetic actuator by open-loop control and a camera device that drives a camera lens by a VCM (voice coil motor).
More specifically, the actuator drive device and the camera device described in PTL 2 do not perform control to feed back a position detection result of a movable portion to a lens position control unit to apply servo, and drive-control the actuator as if a predetermined amount of change was obtained when outputting a predetermined drive current. Accordingly, even when the camera lens is step-driven by open-loop control, by outputting a ramp-wave drive current corresponding to a natural vibration period T to the VCM, natural vibration is prevented from generating in the camera lens after the step drive, and the camera lens can be converged rapidly at a predetermined position. Accordingly, the time required for focus search can be significantly shortened.
In addition, PTL 3 relates to a television camera device having a system for presetting an imaging direction of a television camera by controlling an electric camera platform. The television camera device includes a control means that performs control of the electric camera platform by switching between an open-loop system and a feed-back system (closed-loop control), and the control means controls the television camera device to be at a preset position by performing control by the open-loop system and then performing control by the feed-back system, and performs position correction by the feed-back control after the television camera device is stopped at the preset position.